Release mechanism for a lever jaw wrench



April 12, 1955 H.'A. BERGER RELEASE MECHANISM FOR A LEVER JAW WRENCHFiled Oct. 20, 1951 I N V EN TOR. 361 ?61 United States Patent RELEASEMECHANISM FOR A LEVER JAW WRENCH Harold A. Berger, Plano, 11]., assignorto Metal Engineering Company, Plano, 111., a corporation of IllinoisApplication October 20, 1951, Serial No. 252,249

6 Claims. (Cl. 81-84) This invention relates to a release device for thetoggle mechanism of a lever jaw wrench. In such a tool the togglemechanism comprises a lever in pivotal connection at one end with themovable jaw and at its opposite end in pivotal connection with one endof a link whose opposite end is in pivotal connection with the fixed jawhandle at a point relatively close to its rearward end. In use itsometimes happens that the pivot point of the connection between thelever and link crosses a line between the pivotal connections between(1) the lever with the jaw and (2) the link and the handle. When thisoccurs the movable jaw is locked to the work with such force as not tobe readily disengageable therefrom, and a special release device tobreak the toggle joint in such circumstances becomes highly desirable.

The present invention is concerned with a mechanism for this purpose. ltembodies certain desirable features, such as simplicity in itsconstruction and dependability in its operation. Furthermore, nosupplemental lever is required for operation when the toggle joint is tobe broken, nor any part which, when operated, will engage the fixed jawhandle with possible injury to the fingers it caught therebetween.

These several objects and advantages, as well as others which willhereinafter appear, are accomplished in a highly satisfactory manner bythe mechanism of this invention of which a suggestive embodiment isillustrated in the accompanying drawing in the manner following:

Figure l is a longitudinal sectional view taken centrally through thepresent lever jaw wrench, the toggle mechanism being shown as operatedto a past-center position;

Fig. 2 is a similar view confined to the toggle mechanism and partsimmediately associated therewith, showing the release device in theposition'where it is ready to start operation;

Fig. 3, which is a View similar to Fig. 2, shows the toggle joint brokenas a result of operation of the release device;

Fig. 4 is a fragmentary view in elevation, looking along line 4-4 ofFig. 3; and

Fig. 5 which is a similar view shows a modification in the form of therelease device.

The wrench herein shown comprises a streamlined body which may beproduced from sheet metal reversely bent longitudinally upon itself at 6to provide an open channel defined by a pair of interconnected spacedwalls '7, the channel being somewhat deeper in the head end region thanelsewhere. Away from the head the channel is relatively shallow for anextended distance to provide a fixed handle H. At the head end thespaced walls 7 receive between them a Web 10 to which they are securedas by welding. This web extends centrally from a gripping block 11 thatmay be serrated or otherwise formed upon its work-engaging face.

The part of the wrench which supports the gripping block 11 may betermed the fixed or stationary aw F as distinguished from a coactingmovable aw M which comprises a complementary gripping block 15 thatextends crosswise of a finger 16 that is projected upwardly from a plate17. This plate is extended into the channel of the fixed jaw at the headend region of the wrench and is pivotally connected thereto near itsinner lower corner by a cross pin or rivet 18 at a point that isrelatively deep in the channel.

Extending adjacent the wrench handle H is a lever L, together with anextension piece E, each made desirably 2,705,899 Patented Apr. 12, 1955of sheet metal and longtudinally arched at 21 and 22, respectively, toprovide a rounded outer wall and spaced side walls defining a channelwhich faces the channel of the handle H. This extension piece Econstitutes a movable handle which lies adjacent the channeled handle ofthe wrench to be grasped therewith by the user for manipulation of thewrench. The lever L for part of its length is fitted within thechanneled extension piece E. At a point intermediately of its length,the lever L is connected to the extension piece by a pivot pin a and atits forward end the lever is connected by a pivot b to the movable jaw Mat a point near its outer lower corner. The extension piece E engagesthe lever L in the area of its overlap (see Fig. 1) and serves as anoperating handle therefor, thereby to swing the movable jaw M inwardlywhen the extension piece is pressed toward the fixed handle H inresponse to manual gripping thereof. At its rear end the leverterminates in a heel 23 through which is formed a tapped hole forsupport therein of an adjustable set screw 24 that may be split toprovide spring section for frictionally locking the screw in a selectedposition of axial adjustment.

At a point near the upper end of the extension piece a rearwardlyextending thrust link 30 is in pivotal connection therewith and with thelever L. For this purpose I use the same pivot pin a which interconnectsthe extension piece E and lever L. The pivotal connection a comprised inthe link-lever assembly is referred to sometimes hereinafter as thetoggle joint. At its rear end the thrust link 30 is pivotally connected,as by a pin 0, with a bifurcated head 32 from which is axially extendeda stem 33. This head which constitutes a fulcrum is slidingly fittedwithin the channeled handle H to be guidingly supported thereby. For thepivotal connection 0 I may utilize a pin whose length is approximatelythe same as the inside Width of the channel between the spaced walls 7.

The stem 33 is received within an axial socket 35 at the upper end of anadjusting screw S having at its opposite end a manipulating head 36which lies beyond the proximate end of the fixed handle. The shank ofthe screw is threaded for operative engagement with a bushing 37 that iswelded or otherwise secured in place within the channeled handle H atits lower end. This assembly of adjusting screw S and parts associatedtherewith permits the fulcrum pin c to be adjusted lengthwise of thefixed handle H.

The lever L and its extension piece E constitute, with the thrust link30, a toggle mechanism capable of transmitting a powerful operatingforce to the movable jaw M. This jaw is normally maintained in an openposition by a coiled spring 40 having one end 41 hooked through anopening in the jaw at a point outwardly of its pivotal mounting 18, theopposite spring end 42 being connected to an inset lug 43 that isextended interiorly of the handle H at a point remote from the jaw. Thetension of this spring normally pulls the movable jaw away from thefixed jaw to the extent that is permitted by the linkage in connectiontherewith. An ear 44 projects outwardly from the link oppositely of theset screw 24 to be engaged thereby (see Fig. 1) so that advance of theextension piece E toward the handle H may be halted at a desired point.This car projects a sufficient distance to maintain a minimum separationtherebetween, regardless of the axial position of the set screw.

The mechanism described up to this point provides a powerful lever jawwrench capable of manual operation by a unitary swinging movement of theextension piece E and lever L toward the handle H of the fixed jaw. Inthis operation the toggle joint pivot pin a which interconnects thelever and link will move toward a line xy which passes between the axesof the pivot pins 1) and c. If this movement be not too far, the movablejaw will readily swing back to open position when pressure is relaxedupon the extension piece; if, however, the pivot pin a be movedsufliciently close to the line xy or be shifted over to the far sidethereof (see Fig. 1), then difiiculty is experienced in releasing themovable jaw from its engagement with the work. In such circumstances, tobreak the toggle joint it is necessary to employ a release device ofwhich a preferred form will now be described.

As indicated clearly in Fig. 4, there is extended between the side walls45 of the channeled extension piece E an anchored cross pin 46 locatedinwardly of the lever heel 23 at a point near its lower free end. In theoperated position of the wrench, where its jaws are in engagement withthe work, this cross pin is relatively distant from the lever heel so asto occupy approximately the position of Fig. 1. This position isdetermined by the axial adjustment of the set screw 24, as previouslynoted. If there be resistance to opening of the jaws, due to movement ofthe toggle joint to or beyond the line x-y, then the extension piece Eshould be swung outwardly and away from the fixed jaw handle H. Thefirst stage of this movement is free up to the point of the cross pin 46engaging the lever heel 23. From this point on continued swingingmovement of the extension piece E will carry it through a second stagein which the pin 46 transmits an outward motion to the lever L, therebyto break the toggle joint. In this operation the extension piece E actsas a lever of the second class with the pivot pin a serving as thefulcrum and the cross pin 46 as the resistance point. Due to the factthat the cross pin engages the lever at a point close to its free end, apowerful leverage is available to force the lever outwardly away fromthe handle H of the fixed jaw whereby to break the toggle joint and freethe movable jaw M for disengagement from the work.

As soon as the pivot pin a has passed to the right of the line xy, thespring 40 will exert its tension force through the movable jaw M andtoggle linkage connected therewith to swing the extension piece E to itsfully open position (see Fig. 3) which is reached when the link 3% isdisposed transversely of the lever L at which point a shoulder 48 at thelink end will be in engagement with the lever.

A hole 50 is formed in the arched wall 22 of the ex tension piece,oppositely of the set screw 24, so as to expose its slotted outer endfor manipulation by a screw driver or the like. This is a feature ofadvantage because of the desirability of adjusting the set screw fromtime to time according to the nature of the work upon which the wrenchis required to operate. For example, it may be desired to lock theextension piece-lever assembly relative to the handle H when the jawsare engaged with the work so that the users hand may be relieved fromapplying any further gripping pressure. When this is done, his hand isthen free to manipulate the wrench through a turning movement withouthaving to maintain any gripping pressure on the tool. While adjustmentof the fulcrum pin c is effective to space the jaws apart a selecteddistance prior to one being operated toward the other for gripping ofwork therebetween, the distance of advance of the toggle joint towardthe fixed handle is not directly affected thereby. The extent of thismovement toward or beyond the line .r-y is determined mainly by theposition of the set screw 24. A workman who operates the wrench forrotation of successive work pieces, all alike, will find it advantageousto make the proper adjustments initially before so proceeding.

In Fig. 5 I have illustrated a modified form of release devicecomprising two aligned pins 52 and 53 affixed to the extension pieceside walls 45, inwardly thereof, and in a position to engage the edgesof the lever side walls 55. The spacing between these two pins is suchthat the lever is free to execute its operative movements, but to beengaged by the pins when the extension piece E is swung about the pivota in a direction away from the fixed jaw handle H. When such a movementtakes place, the two pins 52 and 53 are effective to rock the lever Labout its pivotal axis b so as to break the toggle joint thereby torelease the jaws from the work.

In the preceding description I have used in a relative sense the termsupper and lower whose meaning is clear with reference to the illustratedwrench where its head is shown in the up position. In the claims theterm forward and rear have been used with like meanings. These termshave been chosen for convenience in description, and are to be construedas having only relative meaning.

I claim:

1. A wrench of the class described comprising pivotally connectedstationary and movable jaws, the stationary jaw being provided with afixed handle, toggle operating mechanism for the movable jaw comprisinga lever in pivotal connection near one end with the movable jaw andhaving a free end, a link in pivotal connection near one end with thelever intermediately of its ends, and a fulcrum pivotallyinterconnecting the link near its opposite end with the stationary jawhandle at a point relatively near its rear end, an extension piecepivotally connected at its forward end to the lever intermediately ofits ends and extending rearwardly therefrom to engage therewith andprovide therefor a handle opposed to the handle of the stationary jaw tobe grasped simultaneously therewith for moving the lever inwardly tooperate the movable jaw to closed position, said extension piece beingchanneled to face toward the fixed handle of the stationary jaw andhaving spaced side walls between which the lever is disposed, and meanscarried on the side wall of the extension piece, inwardly thereof, inspaced relation to the lever but in position to engage therewith at apoint relatively close to its free end when the extension piece has beenswung away from the fixed handle of the. stationary jaw through apredetermined distance, for transmitting to the lever a retractingmovement relative to the fixed handle of the stationary jaw.

2. A wrench according to claim 1 wherein said means is a pin fixedlyextended crosswise between the spaced side walls of the extension piecein spaced relation to the lever.

3. A wrench of the class described comprising pivotally connectedstationary and movable jaws, the stationary jaw being provided with afixed handle, toggle operating mechanism for the movable jaw comprisinga lever in pivotal connection near one end with the movable jaw, a linkin pivotal connection near one end with the lever, and a fulcrumpivotally interconnecting the link near its opposite end with thestationary jaw handle at a point relatively near its rear end, anextension piece pivotally connected at its forward end to the lever andextending rearwardly therefrom to engage therewith and provide therefora handle opposed to the handle of the stationary jaw to be graspedsimultaneously therewith for moving the lever inwardly to operate themovable jaw to closed position, and a lost motion connection betweensaid extension piece and the lever including means on said extensionpiece positioned to operably contact said lever only after the extensionpiece has been moved away from the fixed handle through a predetermineddistance, additional movement of said extension piece transmitting tothe lever a retracting movement relative to the fixed handle of thestationary jaw.

4. A wrench of the class described comprising pivotally connectedstationary and movable jaws, the stationary jaw being provided with afixed handle, toggle operating mechanism for the movable jaw comprisinga lever in pivotal connection near one end with the movable jaw andhaving a free end, a link in pivotal connection near one end with thelever and a fulcrum pivotally interconnecting the link near its oppositeend with the stationary jaw handle at a point relatively near its rearend, an extension piece pivotally connected at its forward end to thelever and extending rearwardly therefrom to engage therewith and providetherefor a handle opposed to the handle of the stationary jaw to begrasped simultaneously therewith for moving the lever inwardly tooperate the movable jaw to closed position, and lost motion meanscarried by said extension piece underlying and normally spaced from thefree end of said lever when said extension piece is in closed position,said lost motion means including means positioned to contact the freeend of said lever only after the extension piece has been moved awayfrom the fixed handle through a predetermined distance, additionalmovement of said extension piece transmitting to the lever a retractingmovement relative to the fixed handle of the stationary jaw.

5. A wrench of the class described comprising pivotally connectedstationary and movable jaws, the stationary jaw being provided with afixed handle, toggle operating mechanism for the movable jaw comprisinga lever in pivotal connection near one end with the movable jaw andhaving a free end, a link in pivotal connection near one end with thelever and a fulcrum pivotally interconnecting the link near its oppositeend with the stationary jaw handle at a point relatively near its rearend, an extension piece pivotally connected at its forward end to thelever and extending rearwardly therefrom to engage therewith and providetherefor a handle opposed to the handle of the stationary jaw to begrasped simultaneously therewith for moving the lever inwardly tooperate the movable jaw to closed position, said extension piece beingchanneled to face toward the fixed handle of the stationary jaw andhaving spaced walls between which the lever is disposed, a pin fixedlyextended crosswise between the spaced walls of the extension piece inposition to engage therewith at a point relatively close to its free endwhen the extension piece has been swung away from the fixed handle ofthe stationary jaw through a predetermined distance, for transmitting tothe lever 21 retracting movement relative to the fixed handle of the stationary jaw, and stop means between the extension piece and the togglemechanism comprising a set screw carried by the lever in a tapped holein its free end portion oppositely of the link and axially adjustabletoward and from the link and oppositely of a hole in the extension piecethrough which the set screw is accessible for manipulation.

6. In a toggle mechanism, the combination of: a stationary handle; atoggle member pivoted on a first pin carried by said stationary handle;a movable handle pivoted at its upper end on a second pin to said togglemember; a link pivotally connected at its upper end to a third pinlocated on said movable handle, and pivotally engaged to a fourth pin atits lower end, said fourth pin being engaged to the upperend of a firstadjustable screw threaded in the lower end of said stationary handle; asecond adjustable screw threaded in said movable handle in such aposition that it coacts with a stop located intermediate the ends ofsaid link limiting the position of said link to control the ultimateposition of said link relative to said movable handle, said secondadjusting screw having a tool-receiving means and being recessed in saidmovable handle so as to present a continual smooth surface on saidmovable handle.

References Cited in the file of this patent UNITED STATES PATENTS2,443,153 Wells June 8, 1948 2,532,659 Burns Dec. 5, 1950 2,543,922 MeadMar. 6, 1951 2,589,511 Redmon Mar. 18, 1952 2,590,750 Burns Mar. 25,1952 2,592,803 Heim Apr. 15, 1952 2,604,803 McCann July 29, 1952

